Auto tuning the bed heater

I thought I would change the bed heating from bang-bang to PID. It took me a while working through the documentation and the G code wiki to sort out what M code to send. After a couple of false starts I got a result. Actually I got 2 results so I am wondering which one to send with M304.
M307 H0
Heater 0 model: gain 361.6, time constant 647.2, dead time 9.3, max PWM 1.00, mode: PID
Setpoint change: P34.3, I0.053, D223.6
Load change: P34.3, I1.119, D223.6

Warning: Heater 0 appears to be over-powered and a fire risk! If left on at full power, its temperature is predicted to reach 381C.
Auto tune heater 0 with PWM=0.25 completed in 1797 sec, maximum temperature reached 103.5C
Use M307 H0 to see the result

You don't need to use M304 at all. Just put the M307 command with the specified gain, time constant and dead time parameters in config.g. Or, if you are running firmware 1.17 then after running auto tuning you can run M500 to write the M307 command to config-override.g.